#screen {
    width: 450px;
    height: 50px;
    margin-top: 10px;
    background-color: rgba(255, 255, 255,0.7);
    border-radius: 5px;
    font-size: 22px;
    line-height: 50px;
    text-align: center;
}
button {
    width: 450px;
    height: 50px;
    margin-top: 10px;
    background-color: rgba(255, 255, 255,0.7);
    border-radius: 5px;
    font-size: 22px;
    line-height: 50px;
    text-align: center;
    border: none;
    outline: none;
    cursor: pointer;
}
button:hover {
    background-color: #666;
    color: rgba(255, 255, 255);
} 
button:active {
    background-color: rgba(255, 255, 255,0.7);
    color: #666;
} 

